Control method of air conditioner

Abstract

The application relates to the technical field of air conditioning equipment, and particularly provides a control method of an air conditioner, aiming to solve the problem that when the existing air conditioner carries out refrigeration oil return by switching the compressor frequency, the environment is greatly fluctuated, and the use comfort of a user is affected. For the purpose, the control method of the air conditioner comprises the following steps: based on the air conditioner executing an oil return mode, sequentially opening a control valve on an i-th sub-connection pipe, closing control valves on other sub-connection pipes, and making n sub-connection pipes sequentially return oil to the compressor, i is an element in 1~n, so that the speed of gaseous refrigerant in the i-th sub-connection pipe in the on state is increased, the oil in the i-th sub-connection pipe is more conducive to returning to the compressor, and finally the oil return of each sub-connection pipe to the compressor is sequentially completed. The scheme can avoid the great rise and fall of the compressor frequency, prevent the environment from being greatly fluctuated to affect the use comfort of the user, and has good oil return effect.

Description

Technical Field

[0001] This invention relates to the field of air conditioning equipment technology, and specifically provides a control method for an air conditioner. Background Technology

[0002] Multi-split (VRF) air conditioning systems are prone to lubricant buildup due to long piping, significant elevation differences, and numerous bends. Insufficient lubricant in the compressor can easily lead to malfunctions and damage. Therefore, ensuring reliable compressor oil return is crucial for the reliable operation of a VRF air conditioning system. The compressor lubricant is typically mineral oil or POE oil, which is soluble in liquid refrigerant but insoluble in gaseous refrigerant. Consequently, the compressor oil in the system usually accumulates on the walls of the gas pipes.

[0003] For multi-split air conditioners with a three-pipe heat recovery system (where some indoor units operate in cooling mode while others operate in heating mode), there are two gas pipes and one liquid pipe. During cooling operation, the outdoor heat exchanger supplies liquid refrigerant to the indoor heat exchanger via the liquid pipe. The gaseous refrigerant formed after passing through the indoor heat exchanger flows back to the compressor via the two gas pipes. Therefore, in this system, compressor oil is more likely to accumulate on the walls of the two gas pipes. The proposed solution for refrigerant oil return is as follows: after the system has run for a certain period, the compressor switches to medium-high frequency operation. By increasing the return speed and pressure of the gaseous refrigerant in the two gas pipes, the difficulty of oil return and the amount of oil returned are reduced. After the oil return is complete, the compressor switches back to its original frequency. However, switching frequencies causes significant temperature fluctuations in the loop system, affecting user comfort. Frequent oil return requires frequent frequency switching, resulting in even greater temperature fluctuations and further reducing user comfort. Summary of the Invention

[0004] The present invention aims to solve the above-mentioned technical problem, namely, to solve the problem that when existing air conditioners switch compressor frequencies to perform cooling and oil return, the environment experiences large temperature fluctuations, which affects user comfort.

[0005] This invention provides a control method for an air conditioner. The air conditioner includes a compressor, an outdoor heat exchanger, a third connecting pipe, a throttling component, an indoor heat exchanger, and a connecting pipe that are connected in sequence to form a heat pump system. The connecting pipe includes n sub-connecting pipes arranged in parallel, and each sub-connecting pipe is equipped with a control valve, where n≥2. The control method includes: based on the air conditioner executing an oil return mode, sequentially opening the control valve on the i-th sub-connecting pipe and closing the control valves on the other sub-connecting pipes, so that the lubricating oil in the i-th sub-connecting pipe returns to the compressor one by one, where i∈1~n.

[0006] The technical solution provided in this invention involves the following steps during oil return in the cooling operation of an air conditioner: The control valve on the i-th sub-connecting pipe is opened sequentially, while the control valves on the other sub-connecting pipes are closed. This allows the lubricating oil in each of the n sub-connecting pipes to return to the compressor. This increases the velocity of the gaseous refrigerant in the i-th sub-connecting pipe, which is in a conductive state, further facilitating the return of lubricating oil to the compressor. Ultimately, this process completes the sequential return of oil from each sub-connecting pipe to the compressor. This solution avoids large fluctuations in compressor frequency, prevents significant temperature fluctuations in the environment, better ensures user comfort, and provides a more effective oil return process. Attached Figure Description

[0007] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0008] Figure 1 This is a schematic block diagram of the structure of an air conditioner described in some embodiments of this application;

[0009] Figure 2 This is a flowchart of a control method for an air conditioner described in some embodiments of this application;

[0010] Figure 3 This is a flowchart of a control method for an air conditioner according to other embodiments of this application;

[0011] Figure 4 This is a flowchart of a control method for an air conditioner according to some embodiments of this application;

[0012] Figure 5 This is a flowchart of a control method for an air conditioner described in some embodiments of this application;

[0013] Figure 6 This is a flowchart of a control method for an air conditioner according to some embodiments of this application.

[0014] The correspondence between the reference numerals and the component names is as follows:

[0015] 100 Outdoor unit, 200 Indoor unit, 310 First connecting pipe, 311 First control valve, 320 Second connecting pipe, 321 Second control valve, 330 Third connecting pipe, 340 Throttling component, 350 Subcooling valve, 360 Economizer.

[0016] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0017] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0018] The air conditioner provided by this invention, such as Figure 1 As shown, the system includes a compressor, an outdoor heat exchanger, a third connecting pipe 330, a throttling component 340, an indoor heat exchanger, and connecting pipes connected in sequence to form a heat pump system. The connecting pipes include n sub-connecting pipes, each of which is equipped with a control valve, where n ≥ 2.

[0019] In some instances, such as Figure 1 As shown, n=2, the two sub-connecting pipes include a first connecting pipe 310 and a second connecting pipe 320. The control valve on the first connecting pipe 310 is the first control valve 311, and the control valve on the second connecting pipe 320 is the second control valve 321.

[0020] Of course, n=3 or n=4, etc., can also achieve the purpose of this application. Their purpose has not deviated from the design concept of this invention, and will not be elaborated here. They should all fall within the protection scope of this application.

[0021] Furthermore, such as Figure 1 As shown, the air conditioner also includes: a four-way valve, a gas-liquid separator, a subcooling valve 350, and an economizer 360. The compressor's return port is connected to the gas-liquid separator. The gas-liquid separator, connecting pipe, compressor, and outdoor heat exchanger are connected via the four-way valve. Figure 1 As shown, the economizer 360 includes a first internal flow path and a second internal flow path. The end of the third connecting pipe 330 furthest from the outdoor heat exchanger is connected to the throttling component 340 via the first internal flow path. The end of the third connecting pipe 330 furthest from the outdoor heat exchanger is also connected to the second connecting pipe 320 via a subcooling valve 350 and the second internal flow path. The first connecting pipe 310 is a high-pressure pipe, the first control valve 311 is a high-pressure valve, the second connecting pipe 320 is a low-pressure pipe, and the second control valve 321 is a low-pressure valve.

[0022] Alternatively, the first connecting pipe 310 can be a low-pressure pipe, the first control valve 311 a low-pressure valve, the second connecting pipe 320 a high-pressure pipe, and the second control valve 321 a high-pressure valve. In this case, the end of the third connecting pipe 330 away from the outdoor heat exchanger is connected to the first connecting pipe 310 in sequence through the subcooling valve 350 and the second internal flow path (not shown in the figure of this scheme). This can also achieve the purpose of this application. Its purpose has not departed from the design concept of this invention, and will not be elaborated here. It should also fall within the protection scope of this application.

[0023] In some examples, the air conditioner also includes an outdoor unit 100 and an indoor unit 200, the outdoor unit 100 including a four-way valve, a gas-liquid separator, a compressor and an outdoor heat exchanger, and the indoor unit 200 including an indoor heat exchanger.

[0024] In some examples, such as Figure 1 As shown, the air conditioner is a multi-split air conditioner. The outdoor heat exchanger includes one set (which may be one outdoor heat exchanger; or two outdoor heat exchangers; or three outdoor heat exchangers, etc.). The indoor heat exchanger, n sub-connecting pipes, n control valves, third connecting pipe 330 and throttling device 340 are arranged in multiple sets in a one-to-one correspondence (i.e., the indoor heat exchanger, n sub-connecting pipes, n control valves, third connecting pipe 330 and throttling device 340 are arranged in multiple sets in a one-to-one correspondence, and each set includes an indoor heat exchanger, n sub-connecting pipes, n control valves, third connecting pipe 330 and throttling device 340).

[0025] In some embodiments, such as Figure 1 As shown, the first connecting pipe 310, the second connecting pipe 320, the third connecting pipe 330, the first control valve 311, the second control valve 321, and the throttling component 340 include multiple sets of components that are arranged in a one-to-one correspondence.

[0026] It is possible to set multiple groups into two, three, or four groups (e.g., ...). Figure 1 As shown above, all of the above can achieve the purpose of this application. Their purpose has not departed from the design concept of this invention, and will not be repeated here. They should all fall within the protection scope of this application.

[0027] During refrigeration operation, the first control valve 311 and the second control valve 321 are opened, and the subcooling valve 350 is closed. The high-temperature and high-pressure gaseous refrigerant discharged from the compressor outlet passes through the outdoor heat exchanger and the third connecting pipe 330 (in this process, the high-temperature and high-pressure gaseous refrigerant exchanges heat with the outdoor heat exchanger and the third connecting pipe 330 to form a medium-temperature liquid refrigerant, at which time the third connecting pipe 330 is a liquid pipe). Then, it flows from the first internal flow path through the throttling component 340 to the indoor heat exchanger (in this process, the medium-temperature liquid refrigerant passes through the throttling component 340 and enters the indoor heat exchanger to form a low-temperature gaseous refrigerant). Then, the gaseous refrigerant flowing out of the indoor heat exchanger is first split through the first connecting pipe 310 and the second connecting pipe 320, and then flows to the gas-liquid separator. Finally, it flows back to the compressor from the compressor inlet, completing the indoor heat exchanger's function of refrigerating or dehumidifying the indoor environment.

[0028] Alternatively, the throttling component 340 can be configured as an electronic expansion valve; or it can be configured as a capillary tube, etc.; both of these can achieve the purpose of this application, and their purpose has not departed from the design concept of this invention, so they will not be elaborated here, and all should fall within the protection scope of this application.

[0029] The control method for an air conditioner provided by the present invention (not shown in the figure) includes: based on the air conditioner executing the oil return mode, sequentially opening the control valve on the i-th sub-connecting pipe and closing the control valves on other sub-connecting pipes, so that the lubricating oil in the n sub-connecting pipes returns to the compressor one by one, i∈1~n.

[0030] The control method of this air conditioner involves the following steps during oil return in cooling operation: The control valve on the i-th sub-connecting pipe is opened sequentially, while the control valves on the other sub-connecting pipes are closed. This allows the lubricating oil in each of the n sub-connecting pipes to return to the compressor. This increases the velocity of the gaseous refrigerant in the i-th sub-connecting pipe, which is in a conductive state, further facilitating the return of lubricating oil to the compressor. Ultimately, this process completes the sequential return of oil from each sub-connecting pipe to the compressor. This scheme avoids large fluctuations in compressor frequency, prevents significant temperature fluctuations in the environment (i.e., the indoor environment), better ensures user comfort, and provides a more efficient oil return process for the system (i.e., the heat pump system).

[0031] When the air conditioner is running in cooling mode, the timing of the oil return mode can be determined by recording the cooling operation duration (e.g., every 3 minutes, every 5 minutes, every 10 minutes, every 15 minutes, or every 20 minutes). Alternatively, the timing of the oil return mode can be determined by a preset frequency-time ratio based on the actual operating frequency of the compressor. Other methods can also be used to determine when to execute the oil return mode. All of the above can achieve the purpose of this application, and their intent does not depart from the design concept of this invention. They will not be elaborated further here, and all should fall within the protection scope of this application.

[0032] It should be noted that as long as the n sub-connecting tubes are connected one by one, there are no requirements on the connection order of the n sub-connecting tubes. Those skilled in the art can make reasonable settings as needed, which will not be elaborated here, but all should fall within the protection scope of this application.

[0033] In some examples, such as Figure 1 As shown, n=2, the two sub-connecting pipes include a first connecting pipe 310 and a second connecting pipe 320. The control valve on the first connecting pipe 310 is the first control valve 311, and the control valve on the second connecting pipe 320 is the second control valve 321. The steps of sequentially opening the control valve on the i-th sub-connecting pipe and closing the control valves on the other sub-connecting pipes to allow the lubricating oil in the n sub-connecting pipes to return to the compressor include: Figure 2 As shown, first open the first control valve 311 and close the second control valve 321 to return the lubricating oil in the first connecting pipe 310 to the compressor; then close the first control valve 311 and open the second control valve 321 to return the lubricating oil in the second connecting pipe 320 to the compressor.

[0034] When the air conditioner is in cooling operation and in oil return mode: the first control valve 311 is opened and the second control valve 321 is closed. This increases the velocity of the gaseous refrigerant in the first connecting pipe 310, which facilitates the return of lubricating oil from the first connecting pipe 310 to the compressor. The first control valve 311 is closed and the second control valve 321 is opened. This increases the velocity of the gaseous refrigerant in the second connecting pipe 320, which also facilitates the return of lubricating oil from the second connecting pipe 320 to the compressor. This scheme can avoid large fluctuations in compressor frequency and prevent large temperature fluctuations in the environment, thereby better ensuring user comfort and improving the oil return effect of the system.

[0035] Taking the first connecting pipe 310 and the second connecting pipe 320 as examples where the dimensions and shapes are the same: when the first control valve 311 and the second control valve 321 are opened simultaneously, the speed of the gaseous refrigerant in the first connecting pipe 310 and the speed of the gaseous refrigerant in the second connecting pipe 320 are both approximately V / 2; when the first control valve 311 is open and the second control valve 321 is closed, the speed of the gaseous refrigerant in the first connecting pipe 310 is approximately V; when the first control valve 311 is closed and the second control valve 321 is open, the speed of the gaseous refrigerant in the second connecting pipe 320 is approximately V.

[0036] Alternatively, the first control valve 311 can be closed first, and the second control valve 321 can be opened to allow the lubricating oil in the second connecting pipe 320 to return to the compressor; then the first control valve 311 can be opened and the second control valve 321 can be closed to allow the lubricating oil in the first connecting pipe 310 to return to the compressor. This can also achieve the purpose of this application. Its purpose has not departed from the design concept of this invention, and will not be elaborated here. It should also fall within the protection scope of this application.

[0037] In some examples, such as Figure 2 As shown, after closing the first control valve 311 and opening the second control valve 321 to allow the lubricating oil in the second connecting pipe 320 to return to the compressor, the control method further includes: opening the first control valve 311.

[0038] In some examples, such as Figure 3 As shown, the steps of opening the first control valve 311 and closing the second control valve 321 to allow the lubricating oil in the first connecting pipe 310 to return to the compressor include:

[0039] Open the first control valve 311 and close the second control valve 321;

[0040] Record the independent oil return time t1 of the first connecting pipe 310, and determine whether the first judgment condition t1 < the first time threshold T1 is met;

[0041] If the first judgment condition is met, the step of recording the independent oil return time t1 of the first connecting pipe 310 continues;

[0042] If the first judgment condition is not met, then t1 is reset to zero; the steps of closing the first control valve 311, opening the second control valve 321 to allow the lubricating oil in the second connecting pipe 320 to return to the compressor, and then opening the first control valve 311 include:

[0043] Close the first control valve 311 and open the second control valve 321;

[0044] Record the independent oil return time t2 of the second connecting pipe 320, and determine whether the second judgment condition t2 < the second time threshold T2 is met;

[0045] If the second judgment condition is met, the step of recording the independent oil return time t2 of the second connecting pipe 320 will continue to be executed;

[0046] If the second judgment condition is not met, then t2 is reset to zero, and the first control valve 311 is opened. At this time, the compressor returns to the state where the first connecting pipe 310 and the second connecting pipe 320 return gas simultaneously (at this time, both the first control valve 311 and the second control valve 321 are in the open state).

[0047] That is: such as Figure 3As shown, the steps include: first, opening the first control valve 311 and closing the second control valve 321 to allow the lubricating oil in the first connecting pipe 310 to return to the compressor; then, closing the first control valve 311 and opening the second control valve 321 to allow the lubricating oil in the second connecting pipe 320 to return to the compressor; and then opening the first control valve 311 again.

[0048] Open the first control valve 311 and close the second control valve 321;

[0049] Record the independent oil return time t1 of the first connecting pipe 310, and determine whether the first judgment condition t1 < the first time threshold T1 is met;

[0050] If the first judgment condition is met, the step of recording the independent oil return time t1 of the first connecting pipe 310 continues;

[0051] If the first judgment condition is not met, then t1 is reset to zero, the first control valve 311 is closed, and the second control valve 321 is opened;

[0052] Record the independent oil return time t2 of the second connecting pipe 320, and determine whether the second judgment condition t2 < the second time threshold T2 is met;

[0053] If the second judgment condition is met, the step of recording the independent oil return time t2 of the second connecting pipe 320 will continue to be executed;

[0054] If the second judgment condition is not met, then t2 returns to zero, and the first control valve 311 is opened.

[0055] In other exemplary embodiments, such as Figure 4 As shown, the steps include: first, opening the first control valve 311 and closing the second control valve 321 to allow the lubricating oil in the first connecting pipe 310 to return to the compressor; then, closing the first control valve 311 and opening the second control valve 321 to allow the lubricating oil in the second connecting pipe 320 to return to the compressor; and then opening the first control valve 311 again.

[0056] Open the first control valve 311 and close the second control valve 321;

[0057] Record the return oil time t3;

[0058] If t3 < the first time threshold T1 is true, then continue to execute the step of recording the return oil time t3;

[0059] If T1≤t3<second time threshold T2 is true, then close the first control valve 311, open the second control valve 321, and continue to execute the step of recording the return oil time t3;

[0060] If t3≥T2 holds true, then t3 returns to zero, and the first control valve 311 is opened. At this time, the compressor returns to the state where the first connecting pipe 310 and the second connecting pipe 320 return gas simultaneously.

[0061] In some embodiments, the steps of first opening the first control valve 311 and closing the second control valve 321 to allow the lubricating oil in the first connecting pipe 310 to return to the compressor; then closing the first control valve 311 and opening the second control valve 321 to allow the lubricating oil in the second connecting pipe 320 to return to the compressor; and then opening the first control valve 311 again include:

[0062] Open the first control valve 311 and close the second control valve 321;

[0063] Record the return oil time t3;

[0064] If t3 < the first time threshold T1 is true, then continue to execute the step of recording the return oil time t3;

[0065] If T1 = t3 holds true, then close the first control valve 311 and open the second control valve 321.

[0066] If T1 < t3 < the second time threshold T2 is true, then continue to execute the step of recording the return oil time t3;

[0067] If t3≥T2 holds true, then t3 returns to zero, and the first control valve 311 is opened. At this time, the compressor returns to the state where the first connecting pipe 310 and the second connecting pipe 320 return gas simultaneously.

[0068] In some examples, such as Figure 5 and Figure 6 As shown, before the steps of opening the first control valve 311 and closing the second control valve 321, the control method further includes:

[0069] Obtain the compressor's operating frequency p;

[0070] Based on the second frequency threshold P2≤p<first frequency threshold P1, the compressor is controlled to run at frequency p;

[0071] Based on p < P2 < P1, the compressor is controlled to run at frequency P2.

[0072] Based on P1≤the third frequency thresholdP3≤p, the compressor is controlled to run at frequency P1;

[0073] Based on P1≤p≤P3, the compressor is controlled to operate at frequency p. This scheme results in minimal or no change in compressor frequency, and minimal or no temperature fluctuations in the environment, leading to better user comfort and improved system oil return.

[0074] That is: such as Figure 5 and Figure 6 As shown, before the steps of opening the first control valve 311 and closing the second control valve 321, the control method further includes: obtaining the compressor's operating frequency p;

[0075] Based on P2≤p≤P3, the compressor is controlled to run at frequency p;

[0076] Based on p < P2, the compressor is controlled to run at frequency P2;

[0077] Based on p≥P3, the compressor is controlled to run at frequency P1;

[0078] Among them, P2 < P1 < P3.

[0079] In some examples, such as Figure 5 and Figure 6 As shown, after closing the first control valve 311 and opening the second control valve 321 to allow the lubricating oil in the second connecting pipe 320 to return to the compressor, the control method further includes:

[0080] The compressor is controlled to run at frequency p, that is, the system returns to the compressor frequency before the oil return mode is executed. At this time, the first control valve 311 and the second control valve 321 are also in the open state. This can better ensure user comfort and avoid environmental temperature fluctuations.

[0081] That is: such as Figure 5 and Figure 6 As shown, after closing the first control valve 311 and opening the second control valve 321 to allow the lubricating oil in the second connecting pipe 320 to return to the compressor, the control method further includes:

[0082] Open the first control valve 311 to control the compressor to run at frequency p.

[0083] This invention provides a control method for an air conditioner, such as... Figure 5 As shown, it includes:

[0084] When the air conditioner is in cooling mode, the compressor's operating frequency p is obtained based on the air conditioner's oil return mode.

[0085] Based on P2≤p<P1, the compressor is controlled to run at frequency p;

[0086] Based on P1≤p≤P3, the compressor is controlled to run at frequency p;

[0087] Based on p < P2 < P1, the compressor is controlled to run at frequency P2.

[0088] Based on P1≤P3≤p, the compressor is controlled to run at frequency P1;

[0089] Open the first control valve 311 and close the second control valve 321;

[0090] Record the independent oil return time t1 of the first connecting pipe 310, and determine whether the first judgment condition t1 < T1 is met;

[0091] If the first judgment condition is met, the step of recording the independent oil return time t1 of the first connecting pipe 310 continues;

[0092] If the first judgment condition is not met, then t1 is reset to zero, the first control valve 311 is closed, and the second control valve 321 is opened;

[0093] Record the independent oil return time t2 of the second connecting pipe 320, and determine whether the second judgment condition t2 < T2 is met;

[0094] If the second judgment condition is met, the step of recording the independent oil return time t2 of the second connecting pipe 320 will continue to be executed;

[0095] If the second judgment condition is not met, then t2 is reset to zero, the first control valve 311 is opened, and the compressor is controlled to run at frequency p.

[0096] This invention also provides a control method for an air conditioner, such as... Figure 6 As shown, it includes:

[0097] When the air conditioner is in cooling mode, the compressor's operating frequency p is obtained based on the air conditioner's oil return mode.

[0098] Based on P2≤p<P1, the compressor is controlled to run at frequency p;

[0099] Based on P1≤p≤P3, the compressor is controlled to run at frequency p;

[0100] Based on p < P2 < P1, the compressor is controlled to run at frequency P2.

[0101] Based on P1≤P3≤p, the compressor is controlled to run at frequency P1;

[0102] Open the first control valve 311 and close the second control valve 321;

[0103] Record the return oil time t3;

[0104] If t3 < T1 holds true, then continue with the step of recording the return oil time t3.

[0105] If T1≤t3<T2 holds true, then close the first control valve 311, open the second control valve 321, and continue to execute the step of recording the return oil time t3;

[0106] If t3≥T2 is satisfied, reset t3 to zero, open the first control valve 311, and control the compressor to operate at frequency p.

[0107] In summary, according to the technical solution provided by the embodiments of the present invention, when the air conditioner performs oil return during cooling operation: the control valve on the i-th sub-connection pipe is opened one by one in sequence, and the control valves on other sub-connection pipes are closed, so that the lubricating oil in the n sub-connection pipes returns oil to the compressor one by one. In this way, the speed of the gaseous refrigerant in the i-th sub-connection pipe in the conducting state increases, which is more conducive to the lubricating oil in the i-th sub-connection pipe returning oil to the compressor, and finally each sub-connection pipe is sequentially conducted to return oil to the compressor; this solution can avoid sharp rises and falls in the compressor frequency, prevent large temperature fluctuations in the environment, better ensure user comfort, and achieve a better system oil return effect.

[0108] In the description of the present invention, it should be noted that the orientations or positional relationships indicated by the terms "upper", "lower", "one side", "the other side", "one end", "the other end", "side", "opposite", "four corners", "periphery", "square-shaped structure" and the like are based on the orientations or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred structure must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation on the present invention.

[0109] In the description of the embodiments of the present invention, unless otherwise clearly specified and limited, the terms "connected", "directly connected", "indirectly connected", "fixedly connected", "mounted", "assembled" should be understood in a broad sense, for example, it may be a fixed connection, a detachable connection, or an integral connection; the terms "mounted", "connected", "fixedly connected" may be directly connected to each other, or indirectly connected through an intermediate medium, or may be in communication with each other inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood in specific situations.

[0110] Although the embodiments disclosed in the present invention are as described above, the described contents are only the embodiments adopted for the convenience of understanding the present invention, and are not intended to limit the present invention. Any person skilled in the art to which the present invention pertains may make any modifications and changes in the form and details of implementation without departing from the spirit and scope disclosed by the present invention, but the patent protection scope of the present invention shall still be subject to the definition of the appended claims.

[0111] The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. Any equivalent structural transformations made by using the contents of the specification and accompanying drawings of the present invention under the concept of the present invention, or direct / indirect application in other related technical fields, are all included in the patent protection scope of the present invention.

Claims

1. A control method for an air conditioner, characterized in that, The air conditioner includes a compressor, an outdoor heat exchanger, a third connecting pipe, a throttling device, an indoor heat exchanger, and a connecting pipe connected in sequence to form a heat pump system. The connecting pipe includes n sub-connecting pipes arranged in parallel, each sub-connecting pipe being equipped with a control valve, where n ≥ 2. The control method includes: Based on the air conditioner's oil return mode, the control valve on the i-th sub-connecting pipe is opened one by one and the control valves on the other sub-connecting pipes are closed, so that the lubricating oil in the n sub-connecting pipes returns to the compressor one by one, i∈1~n.

2. The control method for an air conditioner according to claim 1, characterized in that, n=2, the two sub-connecting pipes include a first connecting pipe and a second connecting pipe, the control valve on the first connecting pipe is a first control valve, and the control valve on the second connecting pipe is a second control valve; the step of sequentially opening the control valve on the i-th sub-connecting pipe and closing the control valves on the other sub-connecting pipes, so that the lubricating oil in the n sub-connecting pipes returns to the compressor one by one, includes: First, open the first control valve and close the second control valve to allow the lubricating oil in the first connecting pipe to return to the compressor. Then, close the first control valve and open the second control valve to allow the lubricating oil in the second connecting pipe to return to the compressor.

3. The control method for an air conditioner according to claim 2, characterized in that, The step of opening the first control valve and closing the second control valve to allow the lubricating oil in the first connecting pipe to return to the compressor includes: Open the first control valve and close the second control valve; Record the independent oil return time t1 of the first connecting pipe, and determine whether the first judgment condition t1 < the first time threshold T1 is met; If the first determination condition is met, then continue to execute the step of recording the independent oil return time t1 of the first connecting pipe; If the first condition is not met, then t1 is zeroed out.

4. The control method for an air conditioner according to claim 2, characterized in that, The steps of closing the first control valve and opening the second control valve to allow the lubricating oil in the second connecting pipe to return to the compressor include: Close the first control valve and open the second control valve; Record the independent oil return time t2 of the second connecting pipe, and determine whether the second judgment condition t2 < the second time threshold T2 is met; If the second determination condition is met, then continue to execute the step of recording the independent oil return time t2 of the second connecting pipe; If the second condition is not met, then t2 is zero.

5. The control method for an air conditioner according to claim 2, characterized in that, The steps of first opening the first control valve and closing the second control valve to allow the lubricating oil in the first connecting pipe to return to the compressor, and then closing the first control valve and opening the second control valve to allow the lubricating oil in the second connecting pipe to return to the compressor include: Open the first control valve and close the second control valve; Record the return oil time t3; If t3 < the first time threshold T1 is true, then continue to execute the step of recording the return oil time t3; If T1≤t3<second time threshold T2 is true, then close the first control valve, open the second control valve, and continue to execute the step of recording the return oil time t3; If t3≥T2 holds true, then t3 is zero.

6. The control method for an air conditioner according to any one of claims 1 to 5, characterized in that, Before the step of sequentially opening the control valve on the i-th sub-connecting pipe and closing the control valves on the other sub-connecting pipes, so that the lubricating oil in the n sub-connecting pipes returns to the compressor one by one, the control method further includes: Obtain the compressor's operating frequency p; Based on the second frequency threshold P2≤p<first frequency threshold P1, the compressor is controlled to operate at frequency p; Based on p < P2 < P1, the compressor is controlled to operate at frequency P2.

7. The control method for an air conditioner according to claim 6, characterized in that, After the steps of sequentially opening the control valve on the i-th sub-connecting pipe and closing the control valves on the other sub-connecting pipes, so that the lubricating oil in the n sub-connecting pipes returns to the compressor one by one, the control method further includes: Open the closed control valve to control the compressor to run at frequency p.

8. The control method for an air conditioner according to any one of claims 1 to 5, characterized in that, Before the step of sequentially opening the control valve on the i-th sub-connecting pipe and closing the control valves on the other sub-connecting pipes, so that the lubricating oil in the n sub-connecting pipes returns to the compressor one by one, the control method further includes: Obtain the compressor's operating frequency p; Based on the first frequency threshold P1 ≤ the third frequency threshold P3 ≤ p, the compressor is controlled to operate at frequency P1; Based on P1≤p≤P3, the compressor is controlled to operate at frequency p.

9. The control method for an air conditioner according to claim 8, characterized in that, After the steps of sequentially opening the control valve on the i-th sub-connecting pipe and closing the control valves on the other sub-connecting pipes, so that the lubricating oil in the n sub-connecting pipes returns to the compressor one by one, the control method further includes: Open the closed control valve to control the compressor to run at frequency p.

10. The control method for an air conditioner according to any one of claims 1 to 5, characterized in that, The air conditioner is a multi-split air conditioner. The outdoor heat exchanger includes one set, and the indoor heat exchanger, n sub-connecting pipes, the third connecting pipe, and the throttling component are arranged in multiple sets corresponding to each other.

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